The
Shellfish Farm News
June 2003
New
residents and visitors not aware of the long history of
shellfish farming in Baynes Sound often ask “What is
the environmental impact of shellfish farming?” Most
people are impressed to learn that shellfish farming is
beneficial for the environment, and helps reduce the impacts
of other activities such as fishing and upland development.
For
example, shellfish crops and structures, such as oyster
and mussel rafts, function as floating reefs, providing
habitat for small organisms that feed fish and waterfowl.
The clam netting that covers a small percentage of shellfish
farm beaches protects clam crops that spawn every year and
contribute to wild clam populations relied on by wildlife
and recreational harvesters. By seeding and protecting their
crops, clam growers ensure a continuing population of breeding
clams.
Upland
development such as residential housing, agriculture, highways
construction and golf courses result in an increase in the
amount of nutrients like nitrogen and phosphorus that flow
into the waterways of Baynes Sound. Properly functioning
sewage and septic systems will prevent the input of harmful
levels of bacteria into the water, but elevated levels of
nutrients will remain and will be passed into the ocean
via groundwater and surface run-off. These excess nutrients
fertilize the ocean resulting in an increase in the intensity
of phytoplankton blooms, a type of microscopic algae. These
algae give the water a green or brown colour starting in
the spring and lasting through the fall.
Shellfish
like clams, oysters and mussels thrive on phytoplankton,
in fact it is the only food they eat. However, there can
be too much of a good thing. Excessive phytoplankton blooms
can lead to eutrophication, an oxygen-depleting condition
that results in extensive fish-kills. With their natural
filter-feeding capacity, shellfish have a key role in controlling
excess phytoplankton blooms and thereby reduce the potential
of upland development to cause harmful impacts on marine
life.
The
environmental benefits of shellfish farming are so well
recognized in other parts of the world that governments
actively encourage the development of shellfish farms by
offering economic incentives. The fact that shellfish farming
also creates jobs and valuable export products, as well
as great tasting seafood, makes it an ideal economic activity
for coastal communities.
|
